docs: def find_existing_page(self, titles_hierarchy):
          """
          Find and return existing page matching the given titles hierarchy
          """
          # Step backwards through import doc's titles hierarchy with a parent
          # count which is the offset from the current level to each ancestor
          titles_filters = {'publishing_is_draft': True}
          for parent_count, ancestor_title \
                  in enumerate(titles_hierarchy[::-1]):
              # Convert import doc's ancestor title and parent count into
              # a filter query of the form:
              #    translations__title=<entry (ancestor 0) title>
              #    parent__translations__title=<ancestor 1 title>
              #    parent__parent__translations__title=<ancestor 2 title>
              #    parent__parent__parent__translations__title=<ancestor 3 title>
              parent_path = '__'.join(['parent'] * parent_count)
              filter_name = '%s%stranslations__title' % (
                  parent_path, parent_path and '__' or '')
              titles_filters[filter_name] = ancestor_title
          # Return a corresponding page if one exists
          return self.page_model.objects \
              .filter(**titles_filters) \
              .first()